The present invention relates in general to computer telephony integration (CTI), and more particularly to a method and apparatus for migrating existing PBX software and hardware to a personal computer (PC).
Traditional PBXs (private branch exchanges) arc comprises of proprietary if hardware and software enclosed within a cabinet. Prior art PBXs have proven to be invaluable in providing sophisficated call control and messaging functionality between local and remote subscribers. However, recent advances in the field of CTI have given rise to the need for such prior art PBXs to more easily support third party applications. For example, in most prior art PBXs, additional applications such as ISDN access, CTI support, recorded announcement devices (RADs), call accounting and voice mail can only be supported by adding additional external PCs, interface hardware and software.
The telecommunications industry has recognized the desirability of minimizing the complexity and cost of implementing additional applications on prior art PBXs in the manner described above. The ideal solution to the foregoing problem is seen to be full implementation of PBX functionality on a PC platform. However, a significant obstacle in realizing the objective of full PC implementation of PBX functionality is the difficulty in migrating the existing software and architectures from their traditional proprietary stand-alone environment to an exclusively PC-implemented environment. Specifically, the industry has recognized the desirability of avoiding redevelopment of existing call control software and the desirability of reusing such existing software in order to speed development and leverage existing call control functionality. It is recognized that a PC-based PBX such as described above, would retain the strengths of traditional PBX systems (e.g. fiber connectivity to peripherals, hot swapability of line cards, feature richness, networking, etc.) and provide a much more open environment for the integration of applications than is possible with such prior art PBX systems.
According to the present invention, a method and apparatus are provided for migrating existing embedded PBX hardware and software elements into a PC, giving rise to a fully functional PC-based PBX. The PC-based PBX according to the present invention incorporates a main fiber control card for providing real time services including message and circuit switching add fiber-based peripheral connectivity for supporting voice and signaling information between the PC-based PBX and one or more existing peripherals. A hardware abstraction layer is added over the existing call control software for enabling such software to operate in the PC environment, instead of the traditional proprietary PBX environment. According to the preferred embodiment of the invention, other features are provided such as an emulator running in Windows NT for executing existing PBX call control software designed to run on a non-Windows NT platform; a SCSI emulator for mapping SCSI calls from the existing PBX file system onto a Windows NT file system representing all of the existing PBX files and a digital signal processor (DSP) card for providing tone/conferencing functionality.